Sequelae of World War II: an outbreak of chronic cutaneous nontuberculous mycobacterial infection among Satowanese islanders.

Background: After World War II, residents of Satowan (population, 650 persons), an outer island in the state of Chuuk, Federated States of Micronesia, noted a high prevalence of a chronic, progressive skin disease known locally as "spam."

Methods: Island residents who had chronic, progressive verrucous or keloidal plaques for >3 months were considered case patients. Tissue specimens were obtained for culture, histopathological analysis, mycobacterial polymerase chain reaction (PCR), and comparison with the hsp65 gene of Mycobacterium marinum. We performed a case-control study involving all cases and randomly selected control individuals from the community.

Results: A total of 39 case patients were identified, with a median age of 26.0 years (range, 8-82 years); 74.4% were male, and the mean duration of disease was 12.5 years. A total of 98 control individuals were enrolled. Results of all 19 mycobacterial tissue cultures were negative, and histopathological analysis of all 9 lesions showed suppurative granulomatous inflammation with negative results of mycobacterial and fungal stains. In 7 of 9 paraffin-embedded samples, nontuberculous mycobacterial DNA was detected by PCR, and 2 sequenced products had 95% and 87% identity to M. marinum. All case patients were taro farmers (odds ratio, undefined; P < .01), and among taro farmers, when the analysis was controlled for sex, contact with water-filled World War II-era bomb craters was associated with infection (odds ratio, 8.2; P < .01).

Conclusions: "Spam disease" is a chronic, progressive skin disease of high prevalence on Satowan and is associated with taro farming and contact with World War II-era bomb craters. Histopathological and PCR data demonstrate a nontuberculous mycobacterial infection as the cause.